Making a white oil by two stages of catalytic hydrogenation



3,459,656 MAKING A WHITE OIL BY TWO STAGES OF CATALYTIC HYDROGENATION Maurice K. Rausch, South Holland, 11]., assignor to Sinclair Research, Inc., New York, N.Y., a corporation of Delaware No Drawing. Continuation-impart of application Ser. No. 572,662, Aug. 16, 1966. This application July 20, 1967, Ser. No. 654,716

Int. Cl. Cg 41/00, 23/04 US. Cl. 20857 9 Claims ABSTRACT OF THE DESCLOSURE Technical grade or food grade white mineral oils are directly prepared from lubricating viscosity petroleum fractions by catalytic hydrogenation in two steps. The first hydrogenation step is conducted in the presence of a sulfur-resistant catalyst at relatively severe conditions, while the second hydrogenation is conducted over a supported platinum group metal catalyst at milder conditions. The product recovered from the two step catalytic hydrogenation, depending upon conditions of conversion, is directly usable in white mineral oil applications requiring technical or food grade products.

This application is a continuation-inpart of application of S.N. 572,662, filed Aug. 16, 1966, now abandoned.

This invention relates to a process for the production of white mineral oil. More particularly, this invention concerns a two-stage catalytic hydrogenation process for producing technical grade and food grade white mineral oils of high quality and in high yields.

Conventional methods for refining white mineral oils usually involve treating suitable viscosity grade raw lubricant fractions with very high dosages of sulfuric acid, with subsequent neutralization and water-washing. Disadvantages which can result from this type of processing may include relatively low product yields, acid sludge disposal and pollution problems. Furthermore, such processing of high viscosity fractions is very difficult because of emulsion and settling problems encountered during the operation.

A process has now been discovered whereby unrefined or raw mineral oils can be processed to high grade technical white mineral oils in high yields. This process eliminates by-product disposal and pollution problems and advantageously is capable of handling high viscosity feedstocks. According to the process of the present invention, the mineral lubricating oil feedstock which may be derived from a crude oil of substantial naphthenic content is contacted in a first stage with hydrogen under given hydrogenation conditions in the presence of a sulfur-resistant hydrogenation catalyst. The hydrogenated oil from the first hydrogenation stage is then subjected to a second hydrogenation operation which involves contacting the hydrogenated oil with hydrogen in the presence of a platinum group metal-promoted hydrogenation catalyst under given and less severe reaction conditions than used in the first hydrogenation stage to produce a high quality white mineral oil.

The process of this invention has been found to be particularly effective in providing technical and food grade white mineral oils of high quality and in high yields, e.g. greater than about 90%, when the petroleum lubricating oil fraction is a heavy or light raw distillate oil having a specific dispersion below about 180, for instance obtained by distillation of a naphthenic base light reduced crude such as Gulf Coast and California crudes. The naphthenic oils often have a specific dispersion of atent O at least about 130. The oil feedstocks may have a viscosity in the range of about 50 to 7500 SUS at 100 F. If the oils contain a wax, they are preferably dewaxed prior to the first hydrogenation operation, although the dewaxing can follow the first hydrogenation operation. Dewaxing can be carried out, for example, by using a solvent such as methylethyl ketone and toluene to obtain an oil with a pour point (ASTM D 97) below about 25 F. The pour point necessary after dewaxing is determined by that required in the finished oil.

The hydrorefining treatment in the first stage of the method of this invention is conducted at temperatures of about 600 to 750 F., pressures of about 1500 to 5000 p.s.i.g., weight hourly space velocities (WHSV) of about 0.1 to 0.5, and a hydrogen rate of about 1000 to 5000 s.c.f./ b. When it is desired to conduct the hydrorefining treatment to produce a technical grade oil, preferred operating conditions are temperatures of about 600 to 700 F., about 1500 to 3000 p.s.i.g. pressure, a WHSV of about 0.2 to 0.5, and hydrogen flow rate of about 1000 to 3000 s.c.f./b. Preferred conditions for producing a food grade oil, on the other hand, are temperatures of about 650 to 725 F. pressures of about 2200 to 5000 p.s.i.g., a WHSV of about 0.15 to 0.35, and hydrogen rates of about 1500 to 5000 s.c.f./b.

The hydrogenated oil from the first hydrorefining stage is then subjected to less severe hydrogenation conditions, for example, at temperatures of about 450 (or even of about 650 to 725 F pressures of about 2200 to 5000 p.s.i.g., WHSV of about 0.15, or even about 0.25) to 0.75, and a hydrogen feed rate of about 500 to 5000 s.c.fi/b. To provide the less severe reaction conditions, the average temperature of the second stage hydrogenation is at least about 50, preferably at least about F., less than the first hydrogenation stage. The preferred range of conditions for technical grade oil production are temperatures of about 525 to 650 F., pressures of about 1000 to 3000 p.s.i.g., WHSV of about 0.25 to 0.5, and hydrogen flow rates of about 500 to 3000 s.c.f./b. When the process is operated to produce a food grade oil, the preferred conditions are temperatures of about 450 (or even about 500) to 625 F., pressures of about 2000 to 5000 p.s.i.g., WHSV of about 0.15 (or even about 0.25) to 0.35, and hydrogen flow rates of about 1500 to 5000 s.c.f./b.

The catalyst of the first hydrogenation operation can be of any of the sulfur resistant non-precious metal hydrogenation catalysts, some of which are conventionally employed in the hydrogenation of heavy petroleum oils. Examples of suitable catalytic ingredients are tin, vanadium, members of Group VI-B in the Periodic Table, i.e. chromium, molybdenum and tungsten, and metals of the iron group, i.e. iron, cobalt and nickel. These metals are often present in catalytically effective amounts, for instance, about 2 to 30 weight percent, and may be present in the form of oxides, sulfides, or other form. Mixtures of materials can be employed, for example, mixtures or compounds of the iron group metal oxides or sulfides with the oxides or sulfides of Group VI-B constitute very satisfactory catalysts. Examples of such mixtures or compounds are nickel molybdate, tungstate, or chromate (or thiomolybdate, thiotungstate or thiochromate) or mixtures of nickel or cobalt oxides with molybdenum, tungsten or chromium oxides. As the art is aware, and as the specific examples below illustrate, these catalytic ingredients are generally employed while disposed on a suitable carrier of the solid oxide refractory type, eg a predominantly calcined or activated alumina. Commonly employed catalysts have about 1 to 10% of an iron group metal and 5 to 25% of a Group VI-B metal (calculated as the oxide). Advantageously, the catalyst is cobalt molybdate or nickel molybdate supported on 3 alumina. Such preferred catalysts can be prepared by the method described in US. Patent 2,93 8,002.

As aforementioned, the catalyst of the second hydro genation operation of the present invention is a platinum group metal-promoted catalyst. This catalyst is to be distinguished from the catalysts of the first hydrogenation in that it is not normally considered'to be sulfur-resistant. The catalyst includes catalytically effective amounts of the platinum group metals of Group VIII, for instance platinum, palladium, rhodium or iridium, which are present in catalyticallyeifective amounts, generally in the range of about 0.01 to 2 weight percent, preferably about 0.1 to 1 weight percent. The platinum group metal may be present in the metallic form or as a sulfide, oxide or other combined form. The metal may interact with other constituents of the catalyst but if during use the platinum group metal is present in metallic form, then it is preferred that it be so finely divided that it is not detectable by X-ray diffraction means, i.e. that it exists as crystallites of less than about 50 A. size. Of the platinum group metals, platinum is preferred. If desired, the catalysts of the first and second hydrogenations can be hydrogen purged or prereduced prior to use by heating in the presence of hydrogen, generally at temperatures of about 300 to 600 F. for purging or at about 600 to 800 F. for prereduction.

Although various solid refractory type carriers known in the art may be utilized as a support for the platinum group metal, the preferred support is composed predominantly of alumina of the activated or calcined type. The alumina base is usually the major component of the catalyst, generally constituting at least about 75 weight percent on the basis of the catalyst and preferably at least about 85 to 99.8 percent. The alumina catalyst base can be an activated or gamma-alumina, alumina monohydrate, alumina trihydrate or their mixtures. A catalyst base advantageously used is a mixture predominating in, or containing a major proportion of, for instance about 65 to 95 weight percent of one or more of the alumina trihydrates, bayerite I, nordstrandite or gibbonite, and about 5 to 35 weight percent of alumina monohydrate (boehmite), amorphous hydrous alumina or their mixtures. The alumina base can contain small amounts of other solid oxides such as silica, magnesia, natural or activated clays (such as kaolinite, montmorillonite, halloysite, etc.), titania, zirconia, etc., or their mixtures.

Following eighter of the hydrogenation operations of the present invention the hydrogenated oils in each case may be distilled or topped if desired to remove any hydrocracked or other light materials that may have been formed. The removal of light products increases the flash point of the oil. The degree of topping desired will depend on the particular lubricating oil fraction being hydrogenated and the particular hydrogenation conditions employed. Thus, the amount of topped overhead that may be taken off in the topping or distillation step after either hydrogenation operation may often vary from about 0 to 50%, with 0 to being preferred.

The preparation of technical white mineral oil according to the processes of the present invention is illustrated in detail by the following examples. The raw feedstocks in the examples had specific dispersions in the 140 to 150 range.

Example I This example covers processing of a low viscosity raw lubricant fraction. The starting material was a light raw lubricating oil distillate fraction obtained by vacuum distillation of a Gulf Coast, naphthenic base, light, reduced crude oil having a viscosity SUS at 100 of 54.5 and a Saybolt color of L-16, This oil was hydrogenated at 2,400 p.s.i.g., 650 F., 0.25 weight hourly space velocity and a hydrogen rate of 1500 standard cubic feet of hydrogen per barrel of oil over a cobalt molybdate on alumina catalyst containing 2.7% C00 and 1.9% M00 This hydrogenated product was then subjected to a second hydrogenation operation at a pressure of 2500 p.s.i.g., a temperature of 550 F., a weight hourly space velocity of 0.25 and a hydrogen rate of 2500 standard cubic feet of hydrogen per barrel of feed over a platinum on alumina catalyst containing 0.6% platinum. This material Was then steam distilled to yield 94% technical white mineral oil. The properties of the resulting product are compared in Table I with those of the feedstock and of the specifications established for technical white mineral oil. As Example I illustrates, the products of this invention satisfy the technical mineral oil requirements when processing a low viscosity raw lubricant fraction.

1 21 C.F.R. 121.2589

Example II This example covers processing of a high viscosity raw lubricant fraction. The starting material was a heavy raw lubricating oil distillate fraction obtained by vacuum distillation of a Gulf Coast, naphthenic base, light reduced crude having a viscosity, SUS at F., of 7280 and a Saybolt color of L-l6. This oil was hydrogenated at 2400 p.s.i.g., 700 F., 0.25 weight hourly space velocity and a hydrogen rate of 1500 standard cubic feet of hydrogen per barrel of oil over a cobalt molybdate on alumina catalyst containing 2.7% C00 and 11.9% M00 This hydrogenated oil was then subjected to a second hydrogenation operation at a pressure of 2400 p.s.i.g., a temperature of 550 F., a weight hourly space velocity of 0.25 and a hydrogen rate of 2500 standard cubic feet of hydrogen per barrel of feed over a platinum on alumina catalyst containing 0.6% platinum. This material was then steam distilled to yield 94% of technical While mineral oil. The properties of the feedstock, the second stage product and the technical white mineral oil specification requirements are compared in Table II. As can be readily seen, the product of Example II meets the technical white mineral oil specification requirements even with a high viscosity product.

TABLE II Technical white mineral oil Feedstock Product specifications 1 Viscosity, SUS at 100 F 7, 280 2, 053 Color, Saybolt L-16 30+ 20 Min Distillation range, 5-95%, F 849-1, 000 743-939 UV absorbance per centimeter optical pathlength at 280-289 mlml 0. 239 4 0 Max 290-299 mmu 0. 203 3. 3 Max 300-329 mmu 0. 200 2 3 Max 330-350 mmu 0. 089 O. 8 Max 21 C.F.R. 121.2589

Technical white mineral oil has many applications such as, for example, in the production of articles that contact food, as defoaming agents for coatings and the manufacture of textiles and textile fibers.

The preparation of food grade white mineral oil according to the process of the present invention is illustrated in detail by the following example.

Example III A raw, light, naphthenic base lube stock obtained by distillation of naphthenic type crude was subjected to a two stage high pressure catalytic process at the following process conditions.

First Stage Second Stage Nickel moly Platinum on Catalyst on alumina alumina Pressure h drogen artial ressure,

p.s.i.g. p 2, 500 2, 500

Temperature, F 685 680 Weight hourly space val 0. 23 0.23

Hydrogen rate, s.c.f./b 2, 000 2, 400

Overall yield on feedstock was a high 91%. The pertinent tests on the feedstock, product and food grade white mineral oil specifications are listed below.

1 21 O.F.R. 121.1146

Catalysts used in the process described in this example were as follows:

Type

Nickel moly on Platinum on Analyses alumina alumina Ni, Wt. percent 2. 92

Pt, Wt. percent.

M003, Wt. percent 16. S102, Wt. percent 0.325 0. 002 Size (in.) lie Me Food grade white mineral oils have considerable use in food preparations as a defoamer, a release agent, a protective coating and in formulations of binders. Another common use is as a coat on fermentation fluids in the manufacture of wines and vinegar.

What is claimed is:

1. The process for preparing a white mineral oil which comprises first hydrogenating a raw petroleum oil fraction of lubricating viscosity having a specific dispersion below about 180, by contact with hydrogen in the presence of a sulfur-resistant hydrogenation catalyst at a temperature of about 600 to 750 F., a pressure of about 1500 to 5000 p.s.i.g., a weight hourly space velocity of about 0.1 to 0.5, and a hydrogen feed rate of about 1000 to 5000 s.c.f./ b. to provide a hydrogenated oil, and further hydrogenating said hydrogenated oil by contact with hydrogen in the presence of a platinum group metalalumina catalyst at a temperature of about 500 to 700 F., and at least about 50 F. lower than the temperature of the first hydrogenation stage, a pressure of about 1000 to 5000 p.s.i.g., a weight hourly space velocity of about 0.25 to 0.75, and a hydrogen feed rate of about 500 to 5000 s.c.f./b. said hydrogenations serving to provide a White mineral oil product.

2. The process of claim 1 wherein the sulfur-resistant hydrogenation catalyst contains molybdenum and a metal selected from the group consisting of nickel and cobalt.

3. The process of claim 2 wherein the petroleum lubricating oil fraction is obtained by distillation of a naphthenic base crude selected from the class consisting of Gulf Coast and California crudes.

4. The process of claim 3 wherein the raw petroleum lubricating oil fraction has a viscosity, SUS at 100 F. of about 50 to 7500.

5. The process of claim 4 wherein the conditions of the treatment over the sulfur-resistant catalyst are about 600 to 700 F., about 1500 to 3000 p.s.i.g., about 0.2 to 0.5 WHSV and about 1000 to 3000 s.c.f./b. hydrogen rate, the conditions of the treatment over the platinum metal-alumina catalyst are about 525 to 650 F., about 1000 to 3000 p.s.i.g., about 0.25 to 0.5 WHSV and about 500 to 3000 s.c.f./b. hydrogen rate, and the temperature of the latter treatment is at least about F. less than that of the treatment over the sulfurresistant catalyst.

6. The process for preparing a white mineral oil which comprises first hydrogenating a raw petroleum oil fraction of lubricating viscosity having a specific dispersion of less than about 180, by contact with hydrogen in the presence of a sulfur-resistant hydrogenation catalyst at a temperature of about 650 to 725 F., a pressure of about 2200 to 5000 p.s.i.g., a feed rate of about 0.15 to 0.35 WHSV, and a hydrogen flow rate of about 1500 to 5000 s.c.f./b. to provide a hydrogenated oil, and further hydrogenating said hydrogenated oil by contact with hydrogen in the presence of a platinum group metal-alumina catalyst at a temperature of about 450 to 625 F., but at least about 75 F. below the temperature of the first hydrogenation stage, a pressure of about 2000 to 5000 p.s.i.g., a feed rate of about 0.15 to 0.35 WHSV, and a hydrogen feed rate of about 1500 to 5000 s.c.f./b., and recovering a white mineral oil product.

7. The process of claim 6 wherein the sulfur-resistant hydrogenation catalyst contains molybdenum and a metal selected from the group consisting of nickel and cobalt.

8. The process of claim 7 wherein the petroleum lubricating oil fraction is obtained by distillation of a naphthenic base crude selected from the class consisting of Gulf Coast and California crudes.

9. The process of claim 8 wherein the raw petroleum lubricating oil fraction has a viscosity, SUS at F. of about 50 to 7500.

References Cited UNITED STATES PATENTS 2,915,452 12/1959 Fear 208-67 3,328,293 6/1967 Brenken 208-143 3,392,112 7/1968 Bercik et a1. 208-264 HERBERT LEVINE, Primary Examiner US. Cl. X.R. 

